Toaru Kagaku no Railgun SS - Volume 2, Chapter 6

Lou Yao Yao wasted her life fighting over a man, only to find out he wasn’t worth it in the end. Because of this man, she accidentally killed her rival in love, and even ruined the man who had always been watching over her.

Getting reborn as her 20 year old self, there is still time to fix everything. Lou Yao Yao decided to live as a genuine vicious woman. After getting her hands on the loyal like-a-dog man, she would show that cheating couple what pure loving affection looked like.

- Description from Novelupdates

Hazekaya was just an ordinary guy… until he woke up in another world. Sounds exciting, right? WRONG!Before he could even process his isekai moment, he found himself being chased by a horde of horny male orcs.From dodging unwanted “affections”, to getting thrown in jail, to accidentally sleeping in horse crap and earning just enough to not starve. Between dealing with an ex-adventurer boss, getting tricked by his so-called “friends,” and realizing even slimes are harder to kill than he thought, his life in this new world is anything but the overpowered adventure he dreamed of. Instead of becoming a hero, he’s stuck as a low-wage wall repairman, constantly broke, and now the locals call him “Shitman.”With zero cheat skills, no legendary weapons, and a severe lack of dignity, Hazekaya is left wondering—“Why is my isekai life like this!?”

10 years ago, after “the Gate” that connected the real world with the monster world opened, some of the ordinary, everyday people received the power to hunt monsters within the Gate. They are known as “Hunters”.